Work will continue on the decay and processing of RNA in Escherichia coli. This work will concentrate on the enzymes polynucleotide phosphorylase, ribonuclease II, ribonuclease III, ribonuclease H, and ribonuclease M. Some of these enzymes especially ribonuclease M which is a new enzyme discovered in our laboratory, would be further purified and characterized. Mutant strains deficient in the enzymes, ribonuclease I, II, III, P and polynucleotide phosphorylase would be constructed in various combinations, and their physiological properties would be studied with respect to RNA metabolism post-transcription i.e., processing and decay. In processing we shall continue to study mainly, the biosynthesis of ribosomal RNA and in decay, we shall study mainly the fate of mRNA and rRNA.